What is the house edge in roulette?

American roulette has a house edge of 5.26% due to its 0 and 00 pockets. European roulette has a house edge of 2.70% with only a single 0. No betting strategy can eliminate this mathematical edge.

Does the Martingale strategy work in roulette?

The Martingale doubles your bet after every loss. While a single win recovers all losses, a streak of 8 losses turns a $1 base bet into a $256 bet. Table limits and bankroll constraints mean it cannot guarantee long-term profit.

What is the best roulette betting strategy?

No strategy beats the house edge over time. Flat betting minimises variance and bankroll drain. D'Alembert offers gentler progression. Paroli rides winning streaks with winnings rather than your own stake. The best strategy depends on your risk tolerance and session goals.

What is the difference between American and European roulette?

American roulette has 38 pockets (0, 00, and 1-36), giving a house edge of 5.26%. European roulette has 37 pockets (0 and 1-36) and a house edge of 2.70%. All else being equal, European roulette is better for the player.

⬡ ROULETTE CALCULATOR

American Roulette · 38 Pockets · Statistical Analysis

Record spins to generate probability

Last 20 spins

0 spins recorded

W1 — Count Weight 0.50

W2 — Streak Count Weight 0.30

W3 — Miss Streak Weight 0.20

N — History Window (spins)

📈 Betting Zone Scores (lowest % → most probable → best to bet)

⚙ Simulation Config

Spins per Session

Number of Sessions

Bet Type

Zones to Bet per Spin

Betting Strategy

Base Bet (units)

Table Limit (units)

Losses before entry (N)

W1 — Count 0.50

W2 — Streak Count 0.30

W3 — Miss Streak 0.20

N — History Window

📊 Simulation Results

Configure settings on the left and click ▶ Run Simulation.

About This Roulette Calculator

The Roulette Calculator is a free, browser-based tool for tracking live roulette spins and simulating betting strategies across thousands of sessions. It covers every standard betting zone — straight-up numbers, splits, streets, corners, six-lines, dozens, columns, and outside bets — scoring each one using three probability measurements on every spin.

The tool supports both American roulette (38 pockets, 5.26% house edge) and European roulette (37 pockets, 2.70% house edge). Switch between them at the top of the page — all zones, scoring, and simulations update automatically.

For a full breakdown of every bet type, payout, probability, and strategy comparison, see the Roulette Odds & Strategy guide and the Martingale strategy guide.

How the Probability Model Works

Every betting zone is scored each spin using three measurements: how often it has hit compared to expectation (Count), how often it has hit on consecutive spins (Streak Count), and the probability of its current run of misses (Miss Streak). The three scores are combined using adjustable weights that must sum to 1. A lower combined percentage means the zone is hitting less than probability would predict — making it the most probable candidate to bet.

Example Sequence — Black on American Roulette, 10 Rounds
Black · Black · Red · Black · Red · Black · Red · Red · Red · Red
Black hit count = 4  ·  Black streak count = 1  ·  Black miss streak = 4  ·  Rounds = 10  ·  Black spots = 18  ·  Pockets = 38
Scores
Black count        (4/10) ÷ (18/38) = 84.44%  hitting less than expected
Black streak count  (1/10) ÷ (18/38)² = 44.57%  consecutive pairs below expected
Black miss streak   (20/38)⁴ =  7.67%  probability of 4 misses in a row
Default weights applied (Count 0.5 · Streak Count 0.3 · Miss Streak 0.2)
Black count        84.44% × 0.5 = 42.22%
Black streak count  44.57% × 0.3 = 13.37%
Black miss streak    7.67% × 0.2 =  1.53%
Black probability = 42.22% + 13.37% + 1.53% = 57.13%All three measures below expected → Black is most probable to bet. Zones sorted lowest % first.

Weights and history window (N) are adjustable under Settings. Weights auto-normalise to always sum to 1.

Frequently Asked Questions

Does this tool guarantee winning at roulette?

No. The house edge in roulette is mathematical and permanent. This tool helps you understand probability patterns, test betting strategies, and make more informed decisions — but it cannot overcome the structural house advantage of 5.26% (American) or 2.70% (European).

What does P&L mean in the simulator?

P&L stands for Profit and Loss. It represents total winnings minus total stakes wagered across all bets in a session, measured in units (where 1 unit equals your base bet). A result of −52 with a $5 base bet means you lost $260 on average per session.

How accurate is the parameter sweep?

The sweep tests 81 combinations of Count, Streak, and Miss weights across capped sessions for speed. The results indicate relative performance between configurations but should be validated with a full Run Simulation using your preferred settings. All results are subject to the same random variance as real roulette.

What betting strategies does the simulator support?

The simulator supports six strategies: Flat, Martingale, Fibonacci, D'Alembert, Paroli, and Loss Trigger. Each is described in the simulator config panel. For a full comparison of all strategies including bankroll requirements and risk profiles, see the Odds & Strategy guide.

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DISCLAIMER This tool is provided for entertainment and educational purposes only. It does not guarantee winnings or predict future outcomes. Roulette is a game of chance — no betting system or probability model can overcome the mathematical house edge. Never bet more than you can afford to lose. If you or someone you know has a gambling problem, please contact the National Problem Gambling Helpline at 1-800-522-4700 (US) or visit BeGambleAware.org.

      v1.7.1 · American & European Roulette
    